Silver halide emulsions containing yellow dye-forming couplers exhibiting very low pH sensitivity

ABSTRACT

A class of pivalyl aryloxy ketomethylene color-forming coupler compounds exhibit high reactivity with oxidized color developer over a wide range of alkaline pH conditions. Compounds having this unique capability have the structure:   WHEREIN N IS FROM ABOUT 9 TO ABOUT 25 AND M is a monovalent cation.

United States Patent [19] Cameron et al.

[451 July 15,1975

[ SILVER HALIDE EMULSIONS CONTAINING YELLOW DYE-FORMING COUPLERSEXHIBITING VERY LOW pH SENSITIVITY [75] Inventors: Robert G. Cameron,North Chili;

William J. Gass, Rochester, both of N.Y.

[73] Assignee: Eastman Kodak Company,

Rochester, N.Y.

[22] Filed: Nov. 28, 1973 [21] Appl. No.: 419,574

Primary ExaminerJ. Travis Brown Attorney, Agent, or Firm.l. T. Lewis[57] ABSTRACT A class of pivalyl aryloxy ketomethylene colorformingcoupler compounds exhibit high reactivity with oxidized color developerover a wide range of alkaline pH conditions. Compounds having thisunique capability have the structure:

0 n o H C1 II I wherein n is from about 9 to about 25 and M is amonovalent cation.

9 Claims, N0 Drawings SILVER HALIDE EMULSIONS CONTAINING YELLOWDYE-FORMING COUPLERS EXHIBITING VERY LOW PH SENSITIVITY This inventionrelates to color-forming coupler compounds having special utility in thefield of photography. More particularly, the present invention relatesto a special class of ketomethylene yellow dye forming compounds and totheir use in photographic film elements.

Co1or-forming coupler compounds are essential components in many phasesof contemporary color photography. Ordinarily, they react with oxidizedaromatic amino color developing agents to yield colored dyes whichcontribute to the color of the photographic product. The reaction withcolor developing agents takes place during the development" of thephotographic element, after the element has been imagewise exposed.Color developing processes have heretofore required very carefullycontrolled conditions of, for example, time, temperature and pH duringthe various steps of such processes, particularly the step during whichthe reaction of color-forming coupler(s) with oxidized color developermaterial(s) takes place; i.e., the so-called color development ordevelopment step.

One reason for carefully controlling the alkalinity or pH of developersolutions during the color development step of conventional colorphotographic processing is the very sharp drop-off in the color-formingefficiency of the process at relatively lower developer solution pHs.For example, although the Dmax of the yellow dye formed by reaction of aconventional yellow dye-forming coupler with a conventional oxidizedaromatic amino color developer in an otherwise standardized test (whichtest is described in detail in Example 1, below) was 3,40 when aphotographic element was developed at a pH of 11.5, the Dmax was only1.89 when the element was developed at a pH of 10.0. Such a sharpdrop-off in Dmax (with some variation in the extent of drop-off withdecreasing pH from an optimum pH) can be observed almost invariably withcolorforming couplers. Unfortunately the optimum pH for colordevelopment often varies somewhat, depending upon the particular colordeveloper, color-forming coupler, or combination of couplers, beingused. Such variation creates difficulties for those involved in themanufacture of new, commercially acceptable photographic products.

From this it can be appreciated that there is a present need forcolor-forming couplers which exhibit an insensitivity to pH over atleast a large portion of the useful alkaline developer solution pHrange. The existence of pH insensitive couplers would provide greaterflexibility to the formulator of photographic emulsions, and to themanufacturer of color" photographic elements.

DESCRIPTION OF THE INVENTION It has now been discovered that one limitedclass of 2-equivalent pivalyl aryloxy ketomethylene colorformingcouplers has the surprising capability of being practically insensitiveto developer solution pH over a fairly wide range (i.e., pH 9 to pH 12or wider) of developer solution alkalinities.

Compounds having this unusual capability have the structure A:

o 11 0 ll NHSVJ HIIIJ VIL.

((III I C- COOM 5 structures very similar to those of structure Aapparently do not exhibit low insensitivity to pH changes.

DETAILED DESCRIPTION OF THE INVENTION This invention relates to novelcoupler compounds and to photographic emulsions and elements in whichsuch compounds are incorporated.

Although the present invention is broadly applicable to the variouscompounds encompassed by the formula of structure A, set out above, itis generally preferred that M be hydrogen, ammonium or an alkali metalcation such as lithium, sodium or potassium and that n is an average offrom about 1 l to about 19. It is still further preferred that M ishydrogen and n is about 15. After the color-forming couplers of thisinvention are incorporated into a photographic emulsion, the particularidentity of M is extremely difficult to determine, and is unimportantinsofar as the successful practice of this invention is concerned.

The color-forming couplers of this invention are incorporated couplerswhich are present in the photographic element from the time ofmanufacture of said element through the color development step of thedeveloping process. The couplers can be incorporated into thephotographic emulsion during the emulsion manufacturing operation in anyof a number of techniques such as, for example, those described inSection XXII, page of Product Licensing Index, Vol. 92, Dec. 1971.Actually, the particular technique of incorporating the present couplermaterials into the photographic emulsions has little or no effect uponthe successful practice of the present invention. Generally, however,photographic emulsion containing incorporated type couplers which can bedissolved in relatively high boiling coupler solvents (often with theaid of auxiliary solvents in the usual manner) are prepared by firstdispersing in aqueous gelatin solutions the coupler (dissolved in asolvent comprising a high boiling crystalloidal coupler solvent and anauxiliary organic coupler solvent having substantial solubility), thencausing the resulting coupler dispersion in gelatin to set, washing thisset dispersion to remove a substantial amount of the auxiliary solventwith an aqueous solution (at a pH within about 0.5 units of theisoelectric point of the gelatin) of a carboxylic acid having 2-8 carbonatoms such as propionic acid, and subsequently blending the washeddispersion with a gelatino silver halide emulsion.

Similarly, the other specific components which are present in thephotographic emulsions and elements of this invention are not criticalwith respect to the present invention so long as the emulsions arephotosensitive silver halide emulsions. Such emulsions containhydrophilic colloid such as gelatin and can contain addenda, as desired,such as hardeners, antifoggants, sensitizing dyes, chemical sensitizers,coating aids, plasticizers, coupler solvents, matting agents,brightcners, and the like without distracting excessively from thesuccessful practice of the invention. Many examples of such hydrophiliccolloids and addenda, and means for their use can be found in ProductLicensing lndcx, Vol. 92, December 1971, pages l071 l0, publication9232.

The present couplers are ballasted in that they remain essentiallyimmovable in the emulsion, after the emulsion is dried. These couplersconvert into a yellow dye upon reaction with oxidized color developer.For example, upon reaction with N,',1\l-diethylamino-pphenylene diamine,the coupler of Structure A wherein M is hydrogen and n is 15 isconverted into a very desirable yellow dye having a peak absorbance at444.1 nanometers. Because of their yellow dye-producing capability thecouplers of this invention are almost invariably incorporated into theso-called blue sensitive layer ofa 3-color photographic element.Generally, this blue-sensitive layer is the topmost layer of a threelayer element (which may contain additional layers over, between andunder the three basic color-forming layers, as desired), the remainingcolor-forming layers being green-sensitive and red-sensitive," in thetypical, wellknown fashion.

The photographic emulsions of this invention (which contain thecolor-forming coupler compounds of Structure A) are generally coated inany desired manner in the form of at least one layer on a photographicsupport. The particular support that is used is not important withrespect to the successful practice of this invention. Typicalphotographic supports are described and referred to in Product LicensingIndex, Vol. 92, Dec. 1971, Section X.

Organic amino aromatic color developing materials are well known in theart and need not be described in detail here. The couplers of thepresent invention can be developed" with solutions containing anyorganic amino aromatic color developing material that is useful forconventionally color developing photographic elements containingincorporated colorforming couplers. Typical, non-limiting examples ofsuch organic amino aromatic color developing materials includepaminophenol, p-phenylenediamine and N,N-diethyl-pphenylenediamine. Itshould also be noted that, manipulatively, conventional colordevelopment processes can be used successfully to develop photographicelements containing the present couplers incorporated in at least one ofthe layers thereof.

EXAMPLE 1n the following example, all parts given are by weight unlessotherwise specified.

A. A series of photographic elements were prepared by coating in aconventional manner onto a conventional cellulose acetate film supportlayers of photographic emulsions, each containing 1l.l mg/sq. decimeterof silver (as iodobromide) and 2.8 X 10' moles/sq decimeter of yellowdye-forming coupler. Each of the element samples contained a differentcoupler, identified as Coupler 1 through 13, below. The couplers wereincorporated into the emulsion by the method set out in US Pat. No.2,322,027.

B. Each of the elements manufactured in accordance with part A of thisexample was cut into four segments, exposed to a conventional graduateddensity test objcct, and then developed for 4 minutes using Kodak CD-3Developer and processed completely in a conventional way. However, priorto the developing step, the pH developer solution was adjusted byconventional means to pHs of 10.1; 10.5; 11.0; and 11.5. In Table 1,below, are set out the values for Dmax of each of the elements preparedas in paragraph A of this example.

Kodak CD-3 Developer is a solution of 4.5 g sodium sulfite, 36 ganhydrous potassium carbonate, 0.75 g potassium bromide, 0.09 gpotassium iodide, 1.0 g dithiaoctanediol, 0.1 g tetramethyl ammoniumhydrotriborate, and 7.0 g4-amino-3-methyl-N-ethyl-B-(methanesulfonamido)ethylanilinesesquisulfate in water, made to 1 liter.

"pH of developer solution From the data in Table 1, it can readily beappreciated that only coupler number 1 shows consistent nonsensitivityto variations in the pH of developer solutions through the developersolution pH range of from 10 to 1 1.5, while coupler No. 14 demonstratesonly a slight tendency to lose Dmax with decreasing developeralkalinity. The couplers used in this test are identified below. Whilethis test was made using only one color developer solution, it isbelieved that similar comparative results would be obtained using othercolor developer solutions.

Coupler No. 1

nso c n COOHa-Pivalyl-a-(p-carboxyphenoxy)-2-chloro-5-(nhexadecanesulfonamido)acetanilide Coupler No. I I Coupler No.

II II Coupler N0 7 OCH HC-CHZ-OQ C H Coupler No.

(CH3) ccpucwn Q COOII scribed in US Pat. No 3.265506 and 3.408l94 forexample.

The invention has been described in detail with particular reference topreferred embodiments thereof, but, it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

What is claimed is:

l. A light-sensitive silver halide emulsion containing a color-formingcoupler compound capable of high reactivity over a wide alkaline pHrange; said coupler having the structure:

cn o n 0 ll U I n n v y-q CH -C C C C N O O 3 I I H CH ('3 l:l [Cll'--Cll COOM wherein n is an integer from about 9 to about 25 and M ishydrogen or a monovalent cation.

2. A-light-sensitive silver halide emulsion as in claim 1, wherein n isfrom about 11 to about 19.

3. A light-sensitive silver halide emulsion as in claim 1, wherein n isabout 15.

4. A light-sensitive silver halide emulsion as in claim 1, wherein n isabout I l.

5. A photographic element comprising a photographic support coated withat least one photosensitive silver halide emulsion layer; said layercontaining lightsensitive silver halide, hydrophilic colloid, and acoloring couplers, so that competing couplers appear to 40 formingcoupler having the structure:

have relatively little effect on the yellow dye Dmax that can be formedin photographic elements in which the present coupler compounds areincorporated. This particular capability of the coupler compounds ofthis invention (and some other yellow dye-forming coupler compounds) isdetailed at greater length in copending US. Pat. application Ser. No.419,573, filed concurrently herewith, now abandoned, and entitledPhotographic Elements Containing Color-Forming Couplers Having AnInhibiting Effect Upon the Reactivity of Competing Couplers.

The color coupler compounds of this invention can be made by well-knownprocedures such as those dewherein n is an integer from about 9 to about25 and M is hydrogen or a monovalent cation.

6. A photographic element as in claim 5, wherein said color-formingcoupler is present in said layer in an amount equal to about 3 X 10"moles per square decimeter.

7. A photographic element as in claim 6, wherein said n is from about 11to about 19.

8. A photographic element as in claim 6, wherein said n is about 15.

9. A light-sensitive silver halide emulsion as in claim 6, wherein n isabout 1 l.

1. A LIGHT-SENSITIVE SILVER HALIDE EMULSION CONTAINING A COLOR-FORMINGCOUPLER COMPOUND CAPABLE OF HIGH REACTIVITY OVER A WIDE ALKALINE PHRANGE, SAID COUPLER HAVING THE STRUCTURE:
 2. A light-sensitive silverhalide emulsion as in claim 1, wherein n is from about 11 to about 19.3. A light-sensitive silver halide emulsion as in claim 1, wherein n isabout
 15. 4. A light-sensitive silver halide emulsion as in claim 1,wherein n is about
 11. 5. A photographic element comprising aphotographic support coated with at least one photosensitive silverhalide emulsion layer; said layer containing lightsensitive silverhalide, hydrophilic colloid, and a color-forming coupler having thestructure:
 6. A photographic element as in claim 5, wherein saidcolor-forming coupler is present in said layer in an amount equal toabout 3 X 10 5 moles per square decimeter.
 7. A photographic element asin claim 6, wherein said n is from about 11 to about
 19. 8. Aphotographic element as in claim 6, wherein said n is about
 15. 9. Alight-sensitive silver halide emUlsion as in claim 6, wherein n is about11.